Ionized calcium in the atmospheres of two ultra-hot exoplanets WASP-33b and KELT-9b

Yan, F.; Casasayas-Barris, N.; Molaverdikhani, Karan; Alonso-Floriano, F. J.; Reiners, A.; Πάλλη, Ε.; Henning, Th.; Mollière, P.; Chen, G.; Nortmann, L.; Snellen, I. A. G.; Ribas, I.; Quirrenbach, A.; Caballero, J. A.; Amado, P. J.; Azzaro, M.; Bauer, F. F.; Cortés-Contreras, M.; Czesla, S.; Khalafinejad, S.; Lara, L. M.; López‐Puertas, M.; Montes, D.; Nagel, E.; Oshagh, M.; Sánchez-López, A.; Stangret, M.; Zechmeister, M.

doi:10.1051/0004-6361/201936396

Cited by 121 publications

(145 citation statements)

References 61 publications

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“…We then applied the −16 km s −1 ) derived using Kepler's third law with the orbital parameters from Anderson et al (2018). The small ∆ value could originate from several different sources, including the planetary atmospheric motion due to winds or rotation (Zhang et al 2017;Flowers et al 2019), the deviation of the absolute stellar RV relative to the measured RV sys (Yan et al 2019), the uncertainty in the transit ephemeris (e.g. according to the orbital parameters in Anderson et al (2018), the mid-transit time during our observations has an uncertainty of ∼ 300 s, which corresponds to a RV offset of 1.6 km s −1 at phases close to the secondary eclipse), and the eccentricity of the orbit.…”

Section: Cross-correlation Resultsmentioning

confidence: 99%

A temperature inversion with atomic iron in the ultra-hot dayside atmosphere of WASP-189b

Yan

Πάλλη

Reiners

et al. 2020

A&A

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114

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Temperature inversion layers are predicted to be present in ultra-hot giant planet atmospheres. Although such inversion layers have recently been observed in several ultra-hot Jupiters, the chemical species responsible for creating the inversion remain unidentified. Here, we present observations of the thermal emission spectrum of an ultra-hot Jupiter, WASP-189b, at high spectral resolution using the HARPS-N spectrograph. Using the cross-correlation technique, we detect a strong Fe I signal. The detected Fe I spectral lines are found in emission, which is direct evidence of a temperature inversion in the planetary atmosphere. We further performed a retrieval on the observed spectrum using a forward model with an MCMC approach. When assuming a solar metallicity, the best-fit result returns a temperature of 4320−100+120 K at the top of the inversion, which is significantly hotter than the planetary equilibrium temperature (2641 K). The temperature at the bottom of the inversion is determined as 2200−800+1000 K. Such a strong temperature inversion is probably created by the absorption of atomic species like Fe I.

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Section: Cross-correlation Resultsmentioning

confidence: 99%

A temperature inversion with atomic iron in the ultra-hot dayside atmosphere of WASP-189b

Yan

Πάλλη

Reiners

et al. 2020

A&A

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114

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“…The detections of Fe I, Fe II, Ti II (but not of Ti I; Hoeijmakers et al 2018) are confirming the predicted presence of neutral and ionized species in ultra-hot Jupiters. In Cauley et al (2019); Hoeijmakers et al (2019); Yan et al (2019); Turner et al (2020), more neutral and ionized atomic species are reported, such as Na I, Ca I, Ca II, Mg I, Cr II, Sc II, and Y II. In KELT-9 b, ionized species are more abundant than neutral species, which is A. Wyttenbach et al: Hydrogen Balmer series in KELT-9 b thermosphere Table 2.…”

Section: Parametermentioning

confidence: 99%

Mass-loss rate and local thermodynamic state of the KELT-9 b thermosphere from the hydrogen Balmer series

Wyttenbach

Mollière

Ehrenreich

et al. 2020

A&A

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150

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KELT-9 b, the hottest known exoplanet, with Teq ~ 4400 K, is the archetype of a new planet class known as ultra-hot Jupiters. These exoplanets are presumed to have an atmosphere dominated by neutral and ionized atomic species. In particular, Hα and Hβ Balmer lines have been detected in the KELT-9 b upper atmosphere, suggesting that hydrogen is filling the planetary Roche lobe and escaping from the planet. In this work, we detected δ Scuti-type stellar pulsation (with a period Ppuls = 7.54 ± 0.12 h) and studied the Rossiter-McLaughlin effect (finding a spin-orbit angle λ = −85.01° ± 0.23°) prior to focussing on the Balmer lines (Hα to Hζ) in the optical transmission spectrum of KELT-9 b. Our HARPS-N data show significant absorption for Hα to Hδ. The precise line shapes of the Hα, Hβ, and Hγ absorptions allow us to put constraints on the thermospheric temperature. Moreover, the mass loss rate, and the excited hydrogen population of KELT-9 b are also constrained, thanks to a retrieval analysis performed with a new atmospheric model. We retrieved a thermospheric temperature of T = 13 200−720+800 K and a mass loss rate of Ṁ = 1012.8±0.3 g s−1 when the atmosphere was assumed to be in hydrodynamical expansion and in local thermodynamic equilibrium (LTE). Since the thermospheres of hot Jupiters are not expected to be in LTE, we explored atmospheric structures with non-Boltzmann equilibrium for the population of the excited hydrogen. We do not find strong statistical evidence in favor of a departure from LTE. However, our non-LTE scenario suggests that a departure from the Boltzmann equilibrium may not be sufficient to explain the retrieved low number densities of the excited hydrogen. In non-LTE, Saha equilibrium departure via photo-ionization, is also likely to be necessary to explain the data.

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“…One could stack the in-transit spectra at the planetary rest frame and search for absorption features at specific wavelengths (e.g. Redfield et al 2008;Snellen et al 2008;Wood et al 2011;Zhou & Bayliss 2012;Wyttenbach et al 2015Wyttenbach et al , 2017Yan & Henning 2018;Casasayas-Barris et al 2018;Cauley et al 2019;Casasayas-Barris et al 2019;Yan et al 2019;Turner et al 2020). This method works well mostly for strong absorption lines (e.g.…”

Section: S E a R C H I N G F O R At M O S P H E R I C S I G Na L Smentioning

confidence: 99%

Searching for thermal inversion agents in the transmission spectrum of KELT-20b/MASCARA-2b: detection of neutral iron and ionised calcium H&K lines

Nugroho

Gibson

Mooij

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We analyse the transmission spectra of KELT-20b/MASCARA-2b to search for possible thermal inversion agents. The data consist of three transits obtained using HARPSN and one using CARMENES. We removed stellar and telluric lines before cross-correlating the residuals with spectroscopic templates produced using a 1D plane-parallel model, assuming an isothermal atmosphere and chemical equilibrium at solar metallicity. Using a likelihood-mapping method, we detect Fe i at > 13σ, Ca ii H$\&$K at > 6σ and confirm the previous detections of Fe ii, Ca ii IR Triplet, and Na i D. The detected signal of Fe i is shifted by −3.4 ± 0.4 km s−1 from the planetary rest frame, which indicates a strong day–night wind. Our likelihood-mapping technique also reveals that the absorption features of the detected species extend to different altitudes in the planet’s atmosphere. Assuming that the line lists are accurate, we do not detect other potential thermal inversion agents (NaH, MgH, AlO, SH, CaO, VO, FeH, and TiO) suggesting that non-chemical equilibrium mechanisms (e.g. a cold-trap) might have removed Ti- and V-bearing species from the upper atmosphere. Our results, therefore, show that KELT-20b/MASCARA-2b cannot possess an inversion layer caused by a TiO/VO-related mechanism. The presence of an inversion layer would therefore likely be caused by metal atoms such as Fe i and Fe ii. Finally, we report a double-peak structure in the Fe i signal in all of our data sets that could be a signature of atmospheric dynamics. However, further investigation is needed to robustly determine the origin of the signal.

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Ionized calcium in the atmospheres of two ultra-hot exoplanets WASP-33b and KELT-9b

Cited by 121 publications

References 61 publications

A temperature inversion with atomic iron in the ultra-hot dayside atmosphere of WASP-189b

A temperature inversion with atomic iron in the ultra-hot dayside atmosphere of WASP-189b

Mass-loss rate and local thermodynamic state of the KELT-9 b thermosphere from the hydrogen Balmer series

Searching for thermal inversion agents in the transmission spectrum of KELT-20b/MASCARA-2b: detection of neutral iron and ionised calcium H&K lines

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